This protocol will determine the incidence of Mycobacterium tuberculosis (M tb) infection in HIV-infected and -uninfected injecting drug users (IDUs), sexual partners of IDUs, and children in contact with TB-infected adults. It will identify environmental and host risk factors for developing M tb infection; describe the natural history of M tb disease in children and adults; investigate the epidemiology of specific strains of M tb; evaluate the effect of M tb coinfection on the rate of progression of HIV disease; and investigate factors influencing compliance with tuberculosis prophylaxis and therapy.